Drop unused obj_to_primitive() override
Drop unused obj_to_primitive() override

This was a band-aid override until o.vo gained the obj_relationships fix
that this method overrides. That has been in place since o.vo 0.8.0, which
means this is long since no longer necessary (and is actually blocking our
ability to absorb bug fixes to this code in o.vo). Further, we no longer
use this directly because we're doing backports based on version manifests,
which means we no longer consult child_versions _or_ obj_relationships.

Change-Id: Id0ffd492afcbce596b0478fbcacca8bd05736929

devendermishrajio/nova,rajalokan/nova,mikalstill/nova,rajalokan/nova,bigswitch/nova,sebrandon1/nova,Juniper/nova,jianghuaw/nova,openstack/nova,rahulunair/nova,mikalstill/nova,vmturbo/nova,phenoxim/nova,bigswitch/nova,mahak/nova,rajalokan/nova,cyx1231st/nova,cloudbase/nova,Juniper/nova,Juniper/nova,mahak/nova,klmitch/nova,openstack/nova,Juniper/nova,gooddata/openstack-nova,gooddata/openstack-nova,zhimin711/nova,BeyondTheClouds/nova,klmitch/nova,NeCTAR-RC/nova,CEG-FYP-OpenStack/scheduler,vmturbo/nova,phenoxim/nova,klmitch/nova,hanlind/nova,fnordahl/nova,alaski/nova,vmturbo/nova,jianghuaw/nova,jianghuaw/nova,apporc/nova,BeyondTheClouds/nova,rahulunair/nova,sebrandon1/nova,apporc/nova,gooddata/openstack-nova,openstack/nova,gooddata/openstack-nova,CEG-FYP-OpenStack/scheduler,cernops/nova,cloudbase/nova,NeCTAR-RC/nova,mahak/nova,dims/nova,rajalokan/nova,hanlind/nova,vmturbo/nova,fnordahl/nova,klmitch/nova,raildo/nova,cernops/nova,cloudbase/nova,cernops/nova,cyx1231st/nova,rahulunair/nova,raildo/nova,zhimin711/nova,hanlind/nova,dims/nova,jianghuaw/nova,sebrandon1/nova,devendermishrajio/nova,alaski/nova,mikalstill/nova,BeyondTheClouds/nova